We are concerned with numerical computation of shocks whose surfaces are oblique to any axis of grid for computation, where the grid is a structured orthognal grid. It is easily observed that the capturing of shock surface is affected by the grid and that the surface often looks jagged but not smooth, even if the shock surface should be planar or smooth from theory. The phenomenon is purely numerical and the machinery of phenomenon is not yet clear. While the setting of problem is rather simple, several different mathematical factors are complicatedly related even in the case of compressible Euler equations for ideal gases. Therefore we analysis we still obtain some essential part of the numerical machinery, which may suggest a method to decrease the inconvenient effect of grid.会議情報: 第47回流体力学講演会/第33回航空宇宙数値シミュレーション技術シンポジウム (2015年7月2日-3日. 東京大学生産技術研究所), 目黒区, 東京形態: カラー図版ありMeeting Information: 47th Fluid Dynamics Conference /the 33rd Aerospace Numerical Simulation Symposium (July 2-3, 2015. Institute of Industrial Science , the University of Tokyo), Meguro-ku, Tokyo, JapanPhysical characteristics: Original contains color illustrations